Adjustable back for chairs and means for operating same



Feb. 12, 1929; "1,702,016

F. L. MICHEL v ADJUSTABLE BACK FOR CHAIRS AND MEANS FOR OPERATING SA ME Filed June 4, 1926 Patented Feb. 12, T1929.

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ADJUSTABLE BACK FOR CHAIRS AND 3 1351155; OEERATING SAME.

Application filed June a, 1926, serial No. 113,52 3, and in Australia August 27, 1925.

This invention relates to chairs and is particularly applicable to dining chairs, the ob ject being toprovide ordinary straight back chairs with a means whereby the position of the back may be adjusted to various positions according to the requirements of the use.

It is customary withmany types ofchairs to extend the rear legs of the stool portion upwardly and to form the back upon these extended members. The back is therefore rigid and for some purposes is not as com for-table as a chair in which the back lies at an incline to the vertical. w

The present invention may be adjusted for use either as a straight or inclined back by the use of a rack and a simple form of release lever. The side bars of members of the back are extended downwardly and are pivoted near their lower ends to or near the upper ends of the rear legs of the stool por tion, the extended flower portions each being preferably bent or formed so as to bend forwardly beyond the pivotal point. The downward extensions are each provided with a hole to receive the respective end of a double crank that lies cross Wise below the seat. A rack is arranged below the seat, so that the teeth thereon may engage the double crank. A longitudinally slotted lever is pivotally secured in a suitable position below the seat so that the crank may slide therein and be moved into or released from engagement with the teeth on the rack. A spring is provided for the purpose of normally maintaining the crank in engagement with the teeth on the rack.

In the accompanying drawings-- Fig. l is a perspective View of an ordinary dining chair to which my invention is applied the seat being removed to expose the underlying parts.

Fig. 2 is a side view of Fig. 1, certain parts of the chair being broken away in order that the under structure may be clearly illustrated, the upper portion of the back of the chair being also broken away to economize space.

The construction of the stool portion may be greatly varied and is not confined. to the dining chair type shown in the drawings. It may if desired be provided with arm rests although for the sake of simplifying the drawings they have not been shown.

The rear legs extend slightly above the level of the side rails 11 of the seat frame of the stool. The back may be of any suitable design and will be provided with side memberslQ which are extended below the back itself, the extended portions 12* being curved with a forward inclination. These extensions 12?. are each pirotally secured by bolts 18 or other suitable means to the upwardly projecting portions of the legs 10 at a point below the lower horizontal rail of the back. Near the lowerends of the extensions 12' the respective ends of a double crank 14 are pivotally secured at 1d so that the crank lies below the seat and in front of the rear legs.

lrnmediatelybelow the seat the respective ends of two parallel. adjusting rails 15-16 are secured to the front and rear horizontal members 1'?l8 respectively of the seat frame. Upon the underside of the rear half of each of the adjusting rails 15-16 suitably shaped and correspondingly positioned teeth are cut to form a rack 19, such teeth being adapted to engage the central member of the double crank 14. Transversely secured by any suitable means preferably on top of the adjusting rails 1516 are two tie rails and 21 the function of the former being to form a support to which a longitudinally slotted lever 22 may be secured by means of the hinge 23, while that of the latter is to form a bearing surface for a compression spring 24. The central member of the double crank 14 passes through the longitudinal slot 25 which will be formed in the rear half of the lever 22, its length being such as to enable the central member of the crank to slide back and forth therein so that it may be engaged with a correspondingly positioned tooth on each of the adjusting rails 1516. The forward end of the hinged lever 22 may project forwardly to but preferably not beyond the front rail 17 of the seat frame. At suitable positions upon the underside of the tie rail 21 and the upper surface of the hinged lever 22 recesses 2627 will be formed to receive the ends of the helical spring 24: which is normally held in partial compression between those parts. i

In order to alter the angle of the back the forward end of the hinged lever 22 is raised thereby further compressing the spring 24 and causing the rear end of the lever to move downwardly through an are thus causing the central member of the double crank to move downwardly through an arc and thereby releasing the central member of the double crank from engagement with the teeth upon the racks 19. In this position the back of the chair may be moved and its movement will force the central member of the double-crank 14 to slide along the slot 25 according to the direction in which the back is moved and whenthe desired position has been reached by releasing the end of the'lever 22 the spring 24 will operate so as to depress the forward endand raise the rear end of the lever there- 7 by moving the central membeinof the double crank upwardly into engagement with one of the teeth on each of the racks 19 where-it will remain locked. i

f It should be clearly understood that my in vention is not confined to the particular method described above and illustrated in the accompanying sheet of drawings. 1 Other forms of racks may be used'and their position may be altered, the essential features being the downwardly extended side members of the back. 7

I claim 1 I An adjustable back for chairs and for operating same comprising a back having means having a slot therein receiving the double crank and facilitating displacement of the latter, and means normally actuating the lever'to niaintain the crank in-engagement with the rack bars.

' In testimony whereof, I have this 27th day of April, A. D. 1926 signed my name to this specification.

FREDERICK LOUIS MICHEL. 

